The S&P 500 broke through a key technical marker this morning (and then quickly recovered), adding to concerns that this week’s choppy action is the beginning of the market’s long-awaited pullback.

The S&P 500 fell below its 50-day moving average, an indicator that helps chart watchers determine what the market’s next move might be. The last time the index fell below this trend line on an intraday basis was December 31.

But in the last few minutes the market has come roaring back. The S&P 500 recently traded down 0.1% at 1550. The 50-day moving average comes in at about 1544, according to FactSet.

The last time the S&P 500 closed below its 50-day moving average after spending more than three months above it was Oct. 19, 2012. The index fell another 5.6% before bottoming four weeks later.

UPDATE: Stocks have turned south in afternoon trading. As of 3:15 p.m. Eastern Time, the S&P 500 was down 0.7% at 1541, slicing through the 50-day average. Remember, where this closes is important. A final-hour rally would be a positive technical development, while another leg lower cause more jitters in the markets.

Further on the downside, one technician says the “key level” to watch is 1539.

“This represents a double bottom from March 19 and April 5,” says Jonathan Krinsky, chief technical market analyst at Miller Tabak & Co. “Breaking this level, and especially closing beneath 1539 would be a bit of a game changer in our view.”

As we said in today’s Morning MoneyBeat, the S&P 500 started the week with three straight days of more than 1% moves, a pattern that last played out in late February. Per S&P’s data guru Howard Silverblatt, the last time this streak extended to four in a row was in November 2011, when choppy moves of this magnitude were basically commonplace.

The S&P 500 has gone more than 100 trading days since its last 5% pullback, the second longest streak of the current bull market, according to Stone & McCarthy Research Associates.

But ever since hitting a record of 1593 one week ago, the index has now lost about 3%.

Perhaps the market is finally in the midst of the 5% correction so many analysts have been calling for in recent weeks.